With respect to the polyester fibers and fabrics thereof used for fiber products such as a car seat, a roll screen and a filtering medium, for the purpose of the hard finish improving a strength or imparting a hard texture thereto, a resin processing has been commonly performed by using various polymeric compounds.
In addition, in order to impart a flame retardancy to these fiber materials, when the resin processing is performed, it is common that a flame retardant is used together with the resins for processing. However, depending on a flame-retardant level required and a flammability of fiber materials, a flame-retardant treatment is often performed before the resin processing. In this case, even though the fiber materials, which are a base material, become flame-retardant, the resins used for the resin processing burn easily. Therefore, in most cases, the flame retardant must be further used together with the resins.
In that case, the flame retardant which is used together with, damages the drape of fiber or decreases the improvement of strength. Therefore, a large amount of resins is further required in order to prevent these negative effects. Such a use of a large amount of resins disturbs the flame retardancy and as a result, a large amount of flame retardant should be used, which often falls in a vicious cycle.
Conventionally, halogenated flame retardants have been widely used (Patent document 1). However, in recent years, from the viewpoint of prevention of environmental pollution, it has been requested to use a non-halogenated flame retardant. For example, the flame retardants using phosphorous compounds have been used (Patent documents 2 and 3). However, these phosphorous compounds have lower flame retardancy than halogenated compounds. Therefore, it is required to use larger amounts of flame retardant when the phosphorous compound is used instead of the halogenated flame retardant. As a result, there was a defect that it is required to use the same amounts of phosphorous compounds as a resin for processing or larger amounts of phosphorous compounds than a resin for processing.
In addition, since the flame retardant generally has a tendency of inducing a bleed-out of dye, there was a problem that the use of large amounts of the flame retardant lowers the dyeing fastness.